This invention relates to molding apparatus and plastic injection molding methods of producing plastic members incorporating an O-ring retainer and further including products incorporating filtration material molded therein.
There are many applications requiring a molded component to retain an O-ring. In these applications, it is often desirable to provide a groove in a component for receipt of an O-ring that provides a high quality seal at the juncture between the O-ring, the component, and the part which the O-ring encircles, such as a shaft or the like. However, this desirable O-ring feature has been compromised with the need for plastic components that can be manufactured efficiently and cost effectively. For example, in one prior art application requiring a clean hydraulic fluid about a shaft, a plastic member comprising concentric annular ribs with filtration material therebetween was used, with the effective seal between the shaft and the member relying upon a friction fit between an annular rib with filtration material and the shaft. Obviously, such a component is not as effective as an O-ring incorporated therein, which provides a high quality seal with the shaft.
In the manufacturing of plastic parts with interior placed O-rings, grooves on the interior diameter of a part may be made with collapsing cores. Examples of such an apparatus and method to produce such grooves are disclosed in U.S. Pat. Nos. 3,966,385 and 4,044,092. Without detailing their construction herein, suffice it to say that these molds are expensive, complicated, and difficult to maintain due to the complexity of their numerous moving parts that must be actuated during each operating cycle to obtain the desired groove in the resulting plastic parts. Further, they are generally limited in depth of groove creation due to internal geometries of the molding apparatus. Such a method and apparatus, although possible, may not be commercially practicable as to cost effectiveness of the method, resulting component and maintenance of the mold.
Instead of collapsing cores, it is conceivable that an O-ring groove is formed using conventional mold halves to produce two components, each forming only half the groove each, with the components then glued, cemented, melted, or the like together. Such a method is obviously uneconomical and could lead to a less than acceptable O-ring seal due to the multiplicity of parts and the like.
Alternatively, it may be possible to manufacture such a component by placing an O-ring into a two piece mold and molding a component about such an O-ring. However, such an in situ method requires particular component materials and complex interactions between the O-ring material and the overmolded portions of the molded product. Obviously, such a mold and method would involve complex and costly manufacturing apparatus and processes. Further, the resulting product may have inherent structural and material limitations.
The present invention contemplates an apparatus and method for molding a component that incorporates an O-ring retainer that meets the above needs. Specifically, the present invention contemplates a method for molding an O-ring retainer in a molded plastic part comprising, providing a first mold half having an axis, a cavity portion, and a plurality of first and second circumferential teeth about the axis with cavity defining surfaces, the first set having radial ends outward of the axis with surfaces with planar portions closest to the axis, providing a second mold half having an axis, a cavity portion, and a plurality of third and fourth circumferential teeth with cavity defining surfaces angularly displaced about the second mold half axis to mesh with the second and first teeth, respectively, of the first mold half when mated therewith, the second mold half third teeth set having radial ends outward of the second mold half axis with surfaces with planar portions closest to the second mold half axis; translating the first mold half relative to the second mold half along respective axes to thereby mate the first and second mold halves to form a cavity for the molded part; molding the part within the cavity to thereby form a part with a plurality of first and second axially displaced planar surfaces for retaining an O-ring.
Further, the present invention contemplates an apparatus for molding an O-ring retainer in a molded part, said apparatus having an axis of translation, a cavity therein for forming the part, and a parting line, comprising, a first mold half having an axis defining a portion of the cavity, the first mold half having a plurality of circumferential teeth about the axis, the first mold half teeth arranged in at least a first set and second set, the first set having radial ends outward of the first mold half axis with surfaces defining a segment of the cavity with surface portions thereof closest to the first mold half axis; a second mold half having an axis and defining a portion of the cavity, mating the first mold half along a parting line, the second mold half having a plurality of circumferential teeth about the second mold half axis, the second mold half teeth arranged in at least a third and fourth set angularly displaced about the second mold half axis to mesh with the teeth of the first mold half, the third teeth having radial ends outward of the second mold half axis with surfaces defining a segment of the cavity with surface portions thereof closest to the second mold half axis, whereby the cavity formed between the first and second mold halves thereby forms a part having a plurality of first and second segments with surfaces axially displaced from one another for retaining an O-ring.
Still further, the invention contemplates a monolithic molded plastic component adapted for receiving an O-ring comprising a generally plastic member having a bore therethrough, the member having a first and second set of monolithic castellations projecting into the bore and encircling the bore, and having an annular wall between the first and second castellations, thereby defining a gap therebetween into which the O-ring may be received. Further, the present method, apparatus, and component contemplates incorporation of a filtration medium in the plastic component.
Accordingly, the present invention provides, in one form, a plastic injection molded component with a series of molded internal circumferential castellations creating a retainer for an O-ring in the component. These castellations may be of various size and shape to suitably retain a wide range of O-ring of various diameters and exterior configurations. Further, in another form, there is presented in the apparatus a means for creating a filtration window radially outwardly from the O-ring retainer to permit the resulting component to perform a filtration and sealing function. In all forms of the apparatus, method and product herein described, it is believed that cost effective and efficient inventions are presented herein over that presently known. Further, it is believed that the apparatus and method presented herein provide a wide variety of retainer geometry over the apparatus and methods presently known.